Being tall, obese increase blood clot risk

Being tall and obese appears to increase the risk of developing potentially dangerous blood clots in the deep veins, a condition known as deep vein thrombosis (DVT), especially in men.

University of Tromso scientists showed that men who were either obese -- defined as having a body mass index (BMI) of 30 or more -- or tall -- defined as being taller than 1.72 meters, or both are more likely to develop DVT.

While obese men who were taller than 1.82 meters were at fivefold greater risk of developing blood clot, tall but of normal-weighted individuals had a 2.6 times greater risk, according to a studypublished in Arteriosclerosis, Thrombosis, and Vascular Biology.

Compared with short normal-weight men, short and obese ones had a 2.1 greater risk for developing a DVT.

In addition, obese women, regardless of being short or tall, had a slightly greater risk of developing blood clot. There was, however, no increase in the risk of experiencing the condition in tall normal-weight women.

In the present study, women with 1.59 meters or less height were considered as short and those with a BMI of 30 and more were defined as obese.

"The present study is the first to investigate the joint effects of obesity and height on the risk of venous clots," said lead author Sigrid Braekkan.

Obesity had long been considered as a known risk factor for DVT, but the reason behind being tall and having a higher risk of blood clot was a mystery for the researchers.

“In tall people the blood must be pumped a longer distance by the calf-muscle pump, which may cause reduced flow in the legs and thereby raise the risk of clotting,” Braekkan explained as a probable reason behind the findings.